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Studies were carried out to remove uranium from aqueous systems based on the solid phase extraction of uranium by powdered chitin. The effects of various parameters like pH, contact time, and amount of chitin for quantitative sorption of uranium on chitin have been studied. The sorption studies with spiked water samples and natural ground water sam...
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Context 1
... order to study the load factor, 1 L of water was spiked with 5, 10 and up to 1,000 mg uranium (5,000, 10,000 and up to 1,000,000 lg/L) and maintained other optimal parameters as given in Table 2 and the sorption capacity is given in Table 6. It is observed from Table 6, that 1 g chitin can sorb about 300 mg of uranium. ...
Context 2
... order to study the load factor, 1 L of water was spiked with 5, 10 and up to 1,000 mg uranium (5,000, 10,000 and up to 1,000,000 lg/L) and maintained other optimal parameters as given in Table 2 and the sorption capacity is given in Table 6. It is observed from Table 6, that 1 g chitin can sorb about 300 mg of uranium. This clearly indicates that chitin has great potential for the sorption of uranium from mine water and other waste water systems containing uranium. ...
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Citations
... In this case, the preliminary oxidative treatment of black shale raw materials also contributes to the effective conversion of uranium into a productive solution. The obtained uranium-containing solutions have shown full suitability for further sorption extraction methods, including using innovative sorbents [38][39][40][41][42][43][44][45][46][47][48]. An important factor is the economic efficiency of innovation and the calculation of the profitability of using a particular reagent or technology [49][50][51]. ...
The article presents the results of experiments on the extraction of uranium from black shale rock by the combined method of reverse flotation followed by leaching with sulfuric acid. The shape of the uranium in the test sample is typical for such types of black shale rock. The distribution of uranium in silicate and carbon-containing fragments makes it difficult to isolate it by the standard flotation method and reduces extraction by sulfuric acid leaching. Based on the characteristics of the composition of black shale rock, studies were conducted on the extraction of uranium by reverse coal flotation, using various grinding modes and the addition of an oxidizing reagent - trichloroisocyanuric acid (TCCA). The effect of the grinding regime on the transfer of uranium-containing carbon fragments and coal to the reverse flotation concentrate has been revealed. The most representative results of the processing of black shale rock with coarse and fine grinding options are presented. As a result, it was found that when crushed to a fineness class of 60% minus 0.071 mm in the presence of the oxidizer TCCA, the maximum extraction of 98.2% uranium into the tailings during reverse flotation was achieved. Subsequent leaching of the tailings of the reverse flotation made it possible to obtain the maximum concentration of uranium in the productive solution at 94.5% extraction.
... It has been shown that n-ZVI particles are also effective in the removal of radioactive elements from groundwater using PRBs [401][402][403] as well as their reduction by the injection of a colloidal aqueous suspension of n-ZVI particles into the contaminant's flow [404]. In practice, the n-ZVI based composites are used to remove U(VI) ions in: a) mine effluents [63,405], b) contaminated water environment (groundwater) [406][407][408][409], c) treated water [410][411][412]. ...
For almost three decades, the engineered nanomaterials (ENMs) due to their reactivity, unique sorption, catalytic, electronic, optical and magnetic properties, have been the subject of extensive research. The results show that these materials can provide a new tool for the remediation of contaminated aquatic ecosystems (surface and groundwater), sediments, soils, military training grounds and waste recycling areas, including electronic waste. In-situ remediation technologies using composites containing metal nanoparticles, mainly zero-valent iron particles (n-ZVI) are becoming more common. The solutions disclosed in numerous publications and patent applications show their applicability, igher effectiveness and lower costs of remediation processes compared to the conventional methods.
... In this context, the authors developed a simple rapid simultaneous separation and pre-concentration method for the determination of traces of uranium in high TDS natural waters, sea, and brine water. Uranium is commonly separated and pre-concentrated by precipitation methods [9][10][11], ion exchange and chromatographic meth¬ods [12][13][14][15], extraction methods [16][17][18][19], and sorption methods [20][21][22]. Each of these methods has merits and limitations in their application. ...
Investigations were carried out for separation/pre concentration of uranium from aqueous solutions of different TDS using Powdered Activated Carbon (PAC). Parameters like amount of PAC, contact time, pH, volume of solutions and reagents for desorption were optimized. The sorption of uranium is more than 95% at pH 4-5 using 0.5 gram PAC with a contact time of 10 minutes. The sorbed uranium on PAC is recovered using 0.8N HNO3 and determined by LED Fluorimetry. Method was successfully applied to ground water, sea water and brine water. Methodology is simple, selective, cost effective with minimal skills. RSD of the method varies ± 6-14 %.
... This is attributed to the increase of adsorption sites with the increase of the adsorbent mass. Table 2 shows a comparison between the adsorption capacity of the Salvadora Persica branches adsorbent for U(VI) and Th(IV) ions with the previous studies [25][26][27][28][29][30][31][32][33][34][35][36][37]. The Salvadora Persica branches adsorbent exhibited adsorption capacities 24.85 and 21.21 mg/g for U(VI) and Th(IV) ions respectively, that was by using 0.1 g adsorbent mass which exhibited the highest removal efficiency (shown in Fig. 6) Although the exhibited adsorption capacities by the Salvadora Persica branches adsorbent are relatively low, they are comparable with a number of reported values in the literature. ...
Adsorption isotherms of U(VI) and Th(IV) in water were obtained and removal kinetics was studied. The main functional groups on the surface of Salvadora Persica branches adsorbent were identified using a Fourier-transform infrared and the surface morphology of adsorbent was characterized by a Scanning Electron Microscope. Effects of the U(VI) and Th(IV) initial concentrations, contact time, the mass of adsorbent loading, pH of the solution were investigated at 25 ± 0.3 °C. The efficiencies with which this adsorbent removes U(VI) and Th(IV) from their solutions in water are reported. The adsorption isotherm fitted the Freundlich model. The adsorption of U(VI) and Th(IV) follows the pseudo-second order kinetic with squared correlation coefficients (R²) close to 1.0. The thermodynamic parameters (i.e. the free energy (), the enthalpy () and the entropy of adsorption () for the adsorption of U(VI) and Th(IV) on the Salvadora Persica branches adsorbent were reported.
... Wykazano, że cząstki n-Fe(0) są również efektywne w procesach usuwania pierwiastków radioaktywnych z wód gruntowych realizowanych zarówno metodą PRB's [401][402][403], jak i ich redukcji na drodze iniekcji koloidalnej wodnej zawiesiny cząstek n-Fe(0) do pióropuszy zanieczyszczeń [404]. W praktyce kompozyty na bazie n-Fe(0) zastosowano do usuwania jonów U(VI) obecnych w: a) ściekach wód kopalnianych [63,405]; b) zanieczyszczonym środowisku wodnym (wody gruntowe) [406][407][408][409]; c) w wodzie poddawanej uzdatnianiu [410][411][412]. ...
For almost three decades, engineered nanoparticles (ENM’s) have been the subject of intensive research due to their chemical reactivity and their sorption, catalytic, electronic, optical, magnetic and other unique properties. The results obtained indicate that they provide a new tool for the remediation of contaminated aquatic ecosystems (surface and groundwater), sediments, soil training grounds as well as waste recycling areas, e.g. for electronic. The application of in situ restorative technologies using compositions involving metal nanoparticles, mainly iron nanoparticles (n-ZVI, nano zero-valent iron) s becoming more common. Solutions proposed in a number of publications and patents show the versality, greater efficiency and lower costs of the remediation process, compared with conventional methods.
Uranium, a radionuclide, is a predominant element utilised for speciality requirements in industrial applications, as fuels and catalyst. The radioactive properties and chemical toxicity of uranium causes a major threat to the ecosystem. The hazards associated with Uranium pollution includes the cancer in bones, liver, and lungs. The toxicological properties of Uranium are discussed in detail. Although there are many methods to eliminate those hazards, this research work is aimed to describe the application of bioremediation methods. Bioremediation methods involve elimination of the hazards of uranium, by transforming into low oxidation form using natural microbes and plants. This study deeply elucidates the methods as bioleaching, biosorption, bioreduction and phytoremediation. Bioleaching process involves bio-oxidation of tetravalent uranium when it gets in contact with acidophilic metal bacterial complex to obtain leach liquor. In biosorption, chitin/chitosan derived sorbents act as chelators and binds with uranium by electrostatic attraction. Bio reduction employs a bacterial transformation into enzymes which immobilize and reduce uranium. Phytoremediation includes phytoextraction and phytotranslocation of uranium through xylems from soil to roots and shoots of plants. The highest uranium removal and uptake reported using the different methods are listed as follows: bioleaching (100% uranium recovery), biosorption (167 g kg⁻¹ uranium uptake), bioreduction (98.9% uranium recovery), and phytoremediation (49,639 mg kg⁻¹ uranium uptake). Among all the techniques mentioned above, bioleaching has been proved to be the most efficient for uranium remediation.
Uranium contamination in groundwater has been increasingly reported, while biosorbents for the decontamination attracts growing attention because of their distinct advantages of abundant raw materials and eco-friendliness. Herein, a film-like chitin/polyethylenimine biosorbent (CH-PEI) was prepared and employed in the removal of uranyl-carbonate compounds from water. Fourier transform infrared spectra, Element Analysis, Scanning Electron Microscopy/Energy Dispersive X-Ray Spectroscopy, N2 adsorption-desorption isotherms and X-ray Photoelectron Spectroscopy were used to characterize the biosorbent. Besides, thermodynamic calculation and various batch experiments were conducted to investigate the adsorption performances of CH-PEI for uranyl removal from carbonate solution. The results showed that the biosorbent possessed a unique hierarchically porous structure and a high nitrogen content. The batch experiments exhibited that it obtained the maximum adsorption capacity at pH=6. Notably, CH-PEI could reach sorption equilibrium within 4 h at the initial concentration of 50 mg/L. The maximum adsorption capacity were 247.04 mg/g and 1023.74 mg/g at the initial concentrations of 50 mg/L and 300 mg/L. The kinetics and isotherm data were well fitted by pseudo-second-order and Langmuir models. It could remove 98.9% of uranium in the simulated groundwater. The biosorbent showed fast regeneration, good structural stability and reusability in 5 cycles. Furthermore, the adsorption mechanism was confirmed to be anion exchange and electrostatic attraction between nitrogen species and uranyl-carbonate complexes through FT-IR and XPS analysis. Considering its low costs, high efficiency and easy collection, CH-PEI would be a promising biosorbent for uranium removal from groundwater. This study provides a potential technique for uranium removal using chitin-based adsorbents.
In this study, feasibility of modified multi walled carbon nanotubes for removal of trace amounts of Uranium is studied. Multi walled carbon nanotubes were oxidized with HNO3 and then modified with loading 1-(2-pyridylazo)-2-naphtol. The effects of various parameters like pH, contact time, and other factors influenced on removal efficiency of uranium on adsorbent have been studied. Results showed that the method is simple, fast and environmental friendly and it is unaffected by the other ions present in the natural waters. Equilibrium isotherm studies were used to evaluate the maximum sorption capacity of MMWCNTs and experimental. Results showed this to be around 118 mg g-1. The Freundlich and Langmuir models have been applied and the data correlate well with Langmuir model and that the sorption is chemical in nature. Thermodynamic parameters showed the exothermic heat of adsorption and the feasibility of the process. This method is very applicable for removal of uranium from water.
The carboxymethyl cellulose microsphere loaded with Al(III) (CMC-Al) has been explored for removal of uranium(VI) from U-containing water. Various factors, including pH, adsorbent dosage and uranium(VI) concentration, were tested. Langmuir and Freundlich isotherms were applied to the adsorption data. The thermodynamic parameters such as ΔH°, ΔS° and ΔG° were also evaluated. The mechanism of modification and adsorption on CMC-Al were analyzed by SEM, EDX and XPS. Results show Al (III) was loaded on CMC through ion exchange of sodium ion of CMC. The coordination reaction happened during the adsorption process between CMC-Al and uranium(VI).
